Description This specification relates to air purification for mass transit vehicles. Further, it is a non exclusive object of this specification to provide a system for providing an air purification system for a mass transit vehicle which may provide information to users about the performance of the system in real time. It is typical for indoor public spaces to solely use HVAC systems for air management and air quality control. The goal of these systems is to ensure the levels of dust and bacteria do not exceed that of the air outside. The air is also conditioned to ensure the temperature and humidity are comfortable for people accommodating the space. Mass transit vehicles often employ such HVAC systems for the comfort of passengers. Generally, the cabin or public space are closed to allow the HVAC system to work so that opening are with regard to a mass transit vehicle at ends in doorways or the like. HVAC units act intermediate these ends with ‘fresh air’, mostly unconditioned air entering via the doorways when opened. Given that public health is of greater concern following the outbreak of COVID-19 and that public transport usage has dropped significantly since March 2020, there is clear opportunity in the current climate for an air cleaning system that improves hygiene for passengers. Ionisation and use of Ultra Violet (UV) to clean particulate matter and sanitize air have been used. For example, recently PCT/IB2021/054194 - Frigo Clima Implant SRC) has provide a bespoke box with an inlet and an outlet through which air flows so that there is ionisation with the box and UV light for sanitisation. However, retrofitting to existing HVAC conduit systems can be trouble some and emphasis upon the efficiency of HVAC, ionisation and level of UV light to achieve sanitisation. With PCT/IB2021/054194 for example an ionisation detector is provided at the outlet as a indicator of the efficiency of UV light with adjustments accordingly. The air in the bespoke box is specifically determined but not the whole public space or cabin of a mass transit vehicle nor the effects of having doorways to such spaces and cabins. Such teaching to focus ionisation and any UV light sanitising effect requires close, at the outlet monitoring of ionisation, for perceived best effect.

Providing reassurance to passengers regarding air quality and steps being taken to reduce the likelihood of transmission of viruses will restore public confidence in the usage of public transport and mass transit services. Furthermore, providing an indication of improvements is typically more important than ideal or perfect conditions.

There is, therefore, a need to provide an air purification arrangement for mass transit vehicles which alleviates one or more problems associated with the prior art.

A first aspect provides an air purification arrangement for a mass transit vehicle, the arrangement including at least one air ioniser arrangement capable of being mounted within a passenger compartment of the mass transit vehicle, and at least one ion counter, wherein the air ioniser arrangement is configured to ionise the air, and the ion counter configured to measure the ion level of the air away from the air ioniser arrangement within the passenger compartment.

Typically, the at least one air ioniser is located at a position intermediate the passenger compartment whilst the ion counter is towards an end of the compartment near an entrance or doorway to the compartment.

Normally, the at least one air ioniser is part of a HVAC system and located within ducting for that HVAC system such that there is an air flow through the ducting. Typically, the ion counter is positioned such that it isn’t directly in the air flow.

Possibly, the arrangement includes means for exposure of the air flow to Ultra Violet (UV) light for sanitisation.

Generally, the arrangement is coupled to means to determine the mobility and/or closure status of the passenger compartment whereby the level of ionisation by the ioniser arrangement can be varied dependent whether one or more ends of the compartment or other doorways are open and when the passenger compartment is closed.

Preferably, the air purification arrangement further includes a display arrangement configured to display information about the ion level of the air. The display arrangement is coupled to the ion counter to determine the ion level. The display arrangement may be symbolic with iconography for a plurality of ion levels. These ion levels may be swept arcs, for example 5 concentric arc of the same or different colours with each arc determinant of a level of ion count and/or the level of ionisation by the ioniser. The speed of sweep of the arcs may indicate the degree of ionisation by the ioniser or ionisers whilst the number of arcs the level of ionisation as determined by the ion counter. The number of arcs may be limited by the status of the passenger compartment such as with door open and/or vehicle stationary, intermediate with the compartment in motion but with the ioniser working to reach an optimal state and all arcs displayed indication the compartment condition in terms of ionisation is optimal.

Conveniently, the information displayed on the display arrangement is also an indication of the purity of the air.

An aspect provides a mass transit vehicle including the air purification arrangement described and claimed herein.

A further aspect provides a kit comprising at least one air ioniser arrangement capable of being mounted within a HVAC system of the passenger compartment of a mass transit vehicle, and at least one ion counter, wherein the air ioniser arrangement is configured to ionise the air, and the ion counter configured to measure the ion level of the air.

Embodiments of the charging arrangement are described herein, by way of example with regard to the accompanying drawings in which;-

Figure 1 is a schematic illustration of a mass transit vehicle compartment in accordance with aspects of the present invention; and,

Figure 2 is a schematic illustration of an information display iconography in accordance with aspects of the present invention.

Air purification may give rise to a dramatic reduction in the levels of pollutants, odours and harmful microorganisms present in the air and on surfaces. The systems and methods proposed herein may help to improve public hygiene onboard, reduce the likelihood of disease transmission, delay the onset of allergy symptoms, support cleaning processes and may improve the transportation experience for users. The system and method described herein may also communicate information with the passenger via information screens, a mobile application and print media, in an effort to help instil confidence in the passenger and ensure return visits are more likely.

It is typical for indoor public spaces to solely use HVAC systems for air management and air quality control. The goal of these systems is to ensure the levels of dust and bacteria do not exceed that of the air outside. The air is also conditioned to ensure the temperature and humidity are comfortable for people accommodating the space. These systems are usually multi-stage, combining coarse filters and sometimes HEPA (high-efficiency particulate air) filters to remove particles of varying sizes (according to the size of the filter).

The aim of such an approach is to match the air quality outside; they do not and clean the air that is inside the carriage, in contrast to an air ioniser which actively seeks out organic matter present in the air to discourage recirculation. Outside air, especially in heavily congested inner-city areas, can be heavily polluted with contaminants. Such contaminants may be brought in through the HVAC system onboard trains. Public spaces are also breeding grounds for various microbes. An effective air purification system may eliminate harmful pollutants and viruses to improve safety and reduce the likelihood of the transmission of diseases such as COVID-19.

It is therefore proposed to provide an air purification system in a mass transit vehicle.

Turning now to a discussion of the proposed systems and methods, a bipolar ioniser is a type of ion generator which works by passing the air through a controlled electric field with a high voltage, causing positive and negative ions to disperse into the air stream via corona discharge. Ions then combine with oxygen atoms present in the air, meaning the atoms become charged and decomposition reactions are created. A disadvantage of ionisation is the potential production of ozone in the process and the perceived waste if ionization is conducted generically hence prior use of a chamber or box through which air flows and monitoring of ion levels at the outlet of that box to chamber. This also means retrofitting ionisation systems to existing HVAC systems can be problematic.

Aspects of the present invention provide for ioniser, normally 4 in a typical mass transit passenger cabin, within the existing HVAC ducting. The air is ionised to remove pollutants and a UV light sanitisation process also applied to the ionised particles. The ionisers can continuously operate or be switched on or off or more normally the level of ionisation varied dependent upon ion levels determined by an ion counter remote from the ioniser or ionisers. The ionisers are generally intermediate the compartment and the ion counter towards an end or where doors are located. It will be understood a traditional compartment will have end doorways whilst more light railways or trams may have an slide openning possibly in an articulated length with intermediate doors. Fresh, and so probably more particulate laden, air may enter at such door locations so the ion counter near such locations and away from the ioniser or ionisers themselves may be a better indication of ion count and level so particulates in the air.

Air pollutants in the form of molecules suspended in the air attract one another due to opposing polarity and begin to agglomerate; any organic matter is targeted. The agglomeration mechanisms cause the molecules to increase in density and size until they become unsupportable, either falling out of the air or attracting to nearby surfaces due to their inherent charge. By combining this with a mechanical filter which, depending on the size of the pores within the filter, act to remove small particulates present in the air. The two systems complement one another to improve the effectiveness of the air cleaning process.

Positive and negative ions also have microbicidal effects. Ionisation causes production of clusters of hydroxyl (OH) radicals, which are formed on the surface of microbes The OH radicals remove hydrogen from the microbes’ cell walls and cause a disruption of the cell’s surface proteins. Viruses and pathogens which contact the free ions are inactivated when contact is made; direct contact with the ions is required to eliminate infectivity and prevent further transmission.

One example of a potentially suitable air ioniser is an FC-24, 2,400 CFM Autocleaning Needlepoint Bipolar Ionisation (NPBI) System. The features are set out herein - a universal voltage input (24V to 240V AC/DC), operating current of 0.17-0.017A, cleaning cycle current of 0.33-0.03A, consumes 8W power, 50/60Hz frequency, weighs 0.57kg, in-line On/Off switch, programmable autocleaning cycle, operation status LED and replaceable carbon fibre brush emitters. Such a unit is designed to be mounted in-line with a ventilation system inside an airflow duct and does not require regular maintenance. The device also adheres to certifications including UL 867, UL 2998, OSHPD Seismic (OSP), IAQP and CE. Qualifying products must demonstrate they emit less than 0.005 ppm (5 ppb), and the UL 867 requirement of 0.05 ppm (50 ppb) is required for ozone-free certification.

Passing the air through an ionisation field created by NPBI causes compounds to break into one or more of four basic elements: oxygen, nitrogen, carbon dioxide or water vapor, meaning ions are delivered into the air stream free of ozone.

Trial and experimentation of such an ionising device is being carried out, such that the device is in line with a mass transit vehicle’s ventilation system. It is envisaged that such an arrangement will encourage an even distribution of virus-deactivating ions across the saloon. Another part of the proposed air purification package is an ion counter. This device counts free ions in space to determine the ion count at any time. As there is an optimum ion density for a given volume, an ion counter will indicate whether the devices are operating as intended (i.e. releasing a suitable number of ions). It may also suggest whether the ions have distributed evenly throughout the carriage due to the position of the ion counter, which, in the experimental arrangement discussed above, above a ceiling duct near the return air positions near to doors and the like. All devices may be powered by the carriage’s power source and run continuously while the vehicle is in operation to enable a constant stream of purified air.

It is also envisaged that the proposed system and method may provide a clear communication of the purification process to users of the transport and to educate them about on some of the benefits of air ionisation. A feedback loop from the ion counter may feed a digital signal to a Passenger Information Display unit onboard the vehicle that may indicate to the users the progress of the air cleaning through animated visuals. Promotional materials will also include facts relating to the ability of the ioniser to inactivate viruses and remove odours using data that reinforce the hygiene standards of the vehicle.

In this document, a mass transit vehicle may be a train or a bus, and may be an autonomous or driver-controlled vehicle, but it is to be understood that the techniques described herein may be used with any suitable mass-transit vehicle or other vehicle. The techniques may, for example, be applied to cars or lorries, or any other battery- powered vehicle.

Figure 1 provides a schematic illustration of a mass passenger compartment 1 in accordance with aspects of the present invention. The compartment 1 may have end doors 2 and/or side doors 3 with a HVAC system 4 which acts within the compartment 1 to provide air conditioning in terms of temperature and flow. In accordance with the aspects of the present invention at least one and normally as illustrated four ionisers 5 are provided to ionise the air flow such that particulates are removed as discussed above. The level of ionisation can provide a indication of the level of pollutants removed - low ion counts would indicate significant particulates have been removed and as describe above possibly sanitised with UV light.

In accordance with aspects of the present invention ion counters 6 are provided away from the ionisers 5. The counters 6 can be associated with an outside casing of the HVAC ducting or other surface including ceiling of the compartment as with counter 6a or separately as with counter 6b. In either event the counters 6 don’t determine ion count or level directly from the ionisers 5 but ionisation within the compartment 1. The counters 6 are generally located near to opening or doors 2, 3 of the compartmentl as these will be associated with new fresh air entering the compartment 1.

The ion counters 6 will be coupled to a display which will present iconography which will be readily understood. A display 10 is illustrate schematically in figure 2. In a preferred embodiment five arcs 11, 12, 13, 14, 15 are illustrated but more or less could be provided, the objective is to show ion level with each icon arc. As indicated a low ion level or count might indicated that a high proportion of particulates have been remove as the ions will have combined with the particulates and dealt with by a sanitation system such as UV light. Alternatively, a high ion count or level might indicate that there are a large number of ions available to remove particulates. In either event, dependent upon set up, the display 1 can be configure to show a desired level. In such circumstances a first arc 11 may show normally a low level or possibly count of ions indicative of high removal of particulates by the ionisers or a high level meaning a high level of ions and so means to removal of particulates is available. The outer arc 15 will show the opposite with intermediate arcs 12 to 14 having different indications and so visible reassurance to a viewer.

The arcs 11 to 15 could be alternate shapes and may be scan circles concentric about each other. In such circumstances, the level of arc 11 to 15 illuminated may give an indication of ion level whilst the speed of scan sweep the level of ionisation currently being performed by the ioniser or ionisers within the compartment. Typically, the display will have various levels

• STATE 1 - Idle State - Train stationary at a station

The visual indicator is shown to be in a buffering state when the train is stationary with the doors open so fresh particulate laden air will enter the compartment. 10 seconds after the doors have closed, the visual indicator changes to STATE 2

• STATE 2 - In Progress State - Train departing station

The circular motion of the artwork display arcs etc. embodies that the air purification system in progressing to an optimal state. After 30 seconds of this state, the visual indicator moved to STATE 3.

• STATE 3 - System Working Optimally - Train enroute

The visual indicators circular bars align to indicate that the system is working optimally. The visual indicator remains in this state until the next station is reached. While the invention has been illustrated and described in detail in the drawings and preceding description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Each feature of the disclosed embodiments may be replaced by alternative features serving the same, equivalent or similar purpose, unless stated otherwise. Therefore, unless stated otherwise, each feature disclosed is one example of a generic series of equivalent or similar features.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope.